N-substituted alkenyl succinamic acid deicer



N-SUBSTITUTED ALKENYL SUCCINAMIC ACID DEICER Harry Andress, Jr., Pitman, NJ., assignor to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Filed Jan. 16, 1959, Ser. No. 787,133

3 Claims. (Cl. 44-71) This invention relates to gasoline compositions adapted to improve the operation of internal combustion engines. It is more particularly concerned with motor fuels that provide improved engine operation under cool, humid weather conditions.

As is well-known to those skilled in the art, frequent stalling of automobile engines, especially during the warmup period, has been a common occurrence. This difliculty is most pronounced in postwar cars having automatic transmissions and a consequent limit on the maximum permissible idle speed, although it also occurs in cars without automatic transmissions. Stalling of this type, of course, is a definite safety hazard, as Well as a dccided inconvenience in frequent restarting of the engine.

It is now recognized that stalling during the warmup period is attributable to the formation of ice on the throttle plate and the carburetor barrel near it. The water which forms the ice does not come from the gasoline, i.e., as entrained water, but from the air that enters the carburetor. As has been mentioned hereinbefore, stalling generally occurs in cool, humid weather, when the temperatures are above about 30 F. and below about 60 F. and the relative humidity is about 65 percent and higher, up to 100 percent. The most critical conditions are temperatures of 3540 F. and 100 percent relative humidity.

As the gasoline evaporates in the carburetor, it reduces the temperature of the surrounding metal by as much as 40 F. Moisture in the incoming air comes in contact with these parts and begins to build up ice on the throttle plate and in the carburetor barrel. The more moist this air is, the greater the buildup of ice. Then, when the engine is idled, the throttle plate closes and the ice chokes ofi the normal small flow of air through the small clearance between the throttle plate and the carburetor wall. This causes the engine to stall. The engine can usually be restarted when the heat from the exhaust manifold melts the ice sufficiently. However, stalling will continue until the engine is completely warmed up.

Icing may also occur in the carburetors of some vehicles when cruising at speeds of 30-60 m.p.h. Such icing is a particular problem in the case of certain trucks and cars equipped with carburetors having Venturi-type fuel-air mixing tubes (emulsion tubes). Such carburetors are found in trucks and in many European cars. The ice builds up in the tube and restricts the flow of air, thereby enriching the fuel mixture and reducing efiiciency. Eventually the engine may stall.

Gasoline is a mixture of hydrocarbons having an initial boiling point falling between about 75 F. and about 135 F. and an end-boiling point falling between about 250 F. and about 450 F. The boiling range of the gasoline, of course, reflects on its volatility. Thus, a higher boiling gasoline will be less volatile and give less stalling difficulty.. It has been proposed in the art that a gasoline having an A.S.T.M. mid-boiling (50%) point of 310 F.

or higher will not be subject to stalling. Although this may be the case for a given series of gasoline, however,

. Patented May 2, 1 961 2 a it .is not the sole and controlling factor. Gasolines of higher mid-boiling point but a low initial boiling point (e.g., full boiling range gasolines) can induce stalling when the aforementioned stall-inducing atmospheric conditio'ns are prevalent. Thus, any gasoline will give difliculty in damp, cool'weather. In modern engine operation, however, control of stalling by means of volatility is not feasible, because other performance characteristics. are affected.

It has now been found that stalling during engine warmup can be overcome simply and economically. It has been discovered that small amounts of certain N-substituted alkenylsuccinamic acids, when added to motor gasoline, will overcome stalling difficulties attributable to carburetor icing.

Accordingly, it is an object of this invention to provide an improved moto'r fuel. Another object is to provide a motor fuel adapted to prevent stalling during engine.

warmup in cool, humid weather. A specific object is to provide an antistall gasoline containing certain alkenylsuccinamic acids. Other-objects and advantages of this invention will become apparent to those skilled in the art, from the following detailed description.

In general, this invention provides a motor gasoline containing a small amount, sufiicient to inhibit stalling, of the N-(N'aminoethyl)-aminoethyl alkenylsuccinamic acid of an alkenyl succinic acid having the formula:

wherein R is an alkenyl radical containing between 8 and 16 carbon atoms.

The alkenyl succinamic acids contemplated herein are readily prepared by reacting equimolar amounts of an alkenyl succinic acid anhydride and diethylenetriamine, without formation of water of condensation. The condensation takes place readily upon heating the acid anhydride reactant and the diethylenetriamine at temperatures ranging from ambient temperatures and upwards. The reaction is an amide formation reaction effected by the well-known addition of the anhydride group to an amino group. This addition proceeds at any temperature, but temperatures of about C. or lower are preferred. The time of reaction is dependent on the size of the charge and the reaction temperature selected. Ordinarily addition of the acid anhydride is substantially com- CHg-C wherein R is an alkenyl radical having between 8 and.16

carbon atoms and preferably between 10 and 14 carbon? atoms. Non-limiting examples are octenylsuccinic acid" anhydride, diisobutenyl succinic acid anhydride, 2-methyl-g heptenyl succinic acid anhydride, 4-ethyl-hexenyl succinicf acid anhydride, nonenyl succinic acid anhydride,*decenyl succinic acid anhydride, undecenyl succinic acid; anhyrii dride, dodecenyl succinic acid anhydride, triisobutenyl succinic acid anhydride, tetrapropenyl succinic acid 61 ,3. hydride, tetradecenyl succinic acid anhydride, and hexadecenyl succinc acd anhydride.

Although the anhydride is preferred, the compounds contemplated can be prepared from the corresponding alkenyl succinic acid. In this case, thereactionwiththe diethylene triamine is accompanied by formation of one mole of water of condensation per mole of amine. The reaction, in this case, is carried out at temperatures of between about 130 C. and about 160 C., although the reaction can be effected at temperatures above and below this range. The reaction will proceed until one mole of water is evolved per mole of alkenyl succinic acid reactant, usually six to ten hours. In' order to facilitate the removal of water, to effect a more complete reaction in accordance with the principle of Le Chatelier, a hydrocarbon solvent which forms an azeotropic mixture with water can be added to the reaction mixture. Heating is continued until removal of water by azeotropic distillation has substantially ceased. Examples of wellknown solvents that form azeotropes are benzene, toluene, and xylene.

The alkenyl suceinamic acid can exist in either or both of the following structural forms:

R-CH-L-NH CHzCHzNH CHzCHzNH:

O CHr-OH The amount of N-(Naminoethyl) aminoethyl alkenylsuccinami acid that is added to the motor gasoline will vary between about 0.005 percent and about 0.5 percent, by weight, of the gasoline. In preferred practice, amounts varying between about 0.01 percent and about 0.05 percent, by weight, are used The antistall additives of the invention may be used in the gasoline along with other antlstall addition agents or other additives designed to impart other improved properties thereto. Thus, anti-knock agents, pre-ignition inhibitors, anti-rest agents, metal-deactivators, dyes, antioxidants, detergents, etc., may be present in the gasoline. Also, the gasoline may contain a small amount, from about 0.01 percent to about 1 percent, by weight, of a solvent oil or upperlube. Suitable oils, for example, include Coastal and Mid-Continent distillate oils having viscosities within the range of from about 50 to about 500 S.U.S. at 100 F. Synthetic oils, such as diester oils, polyalkylene glycols, silicones, phosphate esters, polypropylenes, polybutylenes and the like, may also be used.

The following examples are for the purpose of illustrating this invention and demonstrating the effectiveness thereof. This invention is not to be limited to the specific compositions set forth in the examples or to 'the operations and manipulations involved. Other materials and formulations as described hereinbefore can be used, as those skilled in the art will readily understand.

The ability of an additive to inhibit icing is demonstrated in the following test:

HILLMAN-MINX ENGINE TEST A downdraft Solex FAI 30 carburetor was mounted on a standard 1953 Hillman-Minx engine. The engine was connected to a 7.5 horsepower induction motor and operated under load at 2800 rpm. This was equiva-- lent to driving at about 40 miles per hour.

The Solex carburetor was especially prone to icing .on its spraying well which is located in the center of the carburetor throat. The spraying well is a cylindrical metal tube with apertures through which a fuel-air mixture. is. sprayed. into. the..carburetor throat. Evaporation. of the fuel refrigerates the spraying well.

As ice formed on the wellit restricted the flow of air through the'carburetor and caused a drop in pressure. This pressure change was recorded by a manometer connected above and below the point of ice deposition. Temperatures at this point were measured by a thermocouple. attached to the well. The entire carburetor was enclosed in an asbestos chamber that was connected to an ice tower. Air at 34-37 F. and 90-100 percent relative humidity was passed through the carburetor at constant velocity.

In conducting a test the engine was first run until the spraying well reached an equilibrium temperature of about 2025 F. The fuel flow was then stopped and the engine was driven by the induction motor until the spraying well reached 45 F. (warm ambient air was admitted to the carburetor during this period). Fuel flow was now restored to the engine and the run was: started. As the engine operated under load, ice deposited. on the spraying well. The pressure drop across the ice formation was recorded at one-minute intervals for 20 minutes. Several tests were made on each fuel blend and the results were averaged.

A fuel rating was obtained by using these pressure readings to calculate the percentage of the carburetor throat area that would be blocked with ice after 20 minutes. The percent of annular area in the carburetor that is blocked by ice determines the amount of pressure drop across the annular opening in any given installation. Thus, for each carburetor, the amount of throat area blocked by ice is related to the amount of pressure drop above and below'the point of ice deposition. The relationship between pressure drop and area blocked was determined to'calibrate the carburetor, as follows:

A series of flanged cylinders were prepared, which fitted over the emulsion tube and blocked a portion of the annular opening. Each tube had a different, but known size flange. Thus, it was known what fraction of the annular area was blocked by each flange. The engine was operated with a flanged cylinder in the carburetor and the amount of pressure drop was noted and recorded. This operation was repeated with each flange.

From thedata, thus obtained, the relationship between pressure drop and amount of throat area blocked was plotted. Then, when runs were made using blank fuel or inhibited (test) fuel, but with no flanged inserts in the carburetor, the throat area blocked by ice was determined from the amount of pressure drop. The average area blocked during the 20-minute run is obtained from the summation of the one-minute observations.

. It will be appreciated, of course, that calibration curves will vary with each carburetor, but any carburetor can be readily calibrated as aforedescribed. As is the case in many test procedures, results can vary from time to time, because of slight variations in test conditions, vapor pressure of fuel, and even techniques of individual operators. Thus, each day a test run is made, a blank fuel should be run. This provides a reference point, so that even if values determined may not be finite, comparison of a testfuel result with the resulton the blank fuel gives Example A succinamic acid was prepared by heating one mole of tetrapropenyl succinic acid anhydride with a mcie of. diethylenetriamine, using a xylene diluent, at. a tempera ture of -90 C for 2 hours. The alkenylgroup of this.

i Z anhydride is a C radical obtained from tetrapropylene, i.-e., propylene tetramer. Blends of this N-( N aminoethyl) aminoethyl tetrapropenylsuccinamic acid in test gasoline were subjected to the Hillman-Minx engine test. Pertinent data and test results are set forth in Table I.

It will be apparent from the data in Table I, that the additives of this invention are effective antistall additives for gasoline. They are not all equivalent in performance, however.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

What is claimed is:

1. A motor gasoline containing a small amount, sulficient to inhibit icing, of the N-(N'aminoethyl)-aminoethyl alkenylsuccinamic acid of an alkenyl succinic acid having the formula:

R-CH-COOH Ha-COOH wherein R is an alkenyl radical containing between v8 and 16 carbon atoms.

2. A motor gasoline containing between about 0.005 percent and about 0.5 percent, by weight, of the N-(N'- am-inoethyl)-aminoethyl alkenylsuccinamic acid of an alkenyl succinic acid having the formula:

- R-OH-COOH CHz-COOH 10 wherein R is an alkenyl radical containing between 8 and 16 carbon atoms.

3. A motor gasoline containing between about 0.01

percent and about 0.05 percent, by weight, of the N- (N'aminoethyl) -aminoethyl tetrapropenylsuccinamic acid.-

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Petroleum Refining with Chemicals, Kalichevsky and Kobe, Elsevier Pub. Co., 1956, page 480. 

1. A MOTOR GASOLINE CONTAINING A SMALL AMOUNT, SUFFICIENT TO INHIBIT ICING, OFTHE N-(N''AMINOETHYL)-AMINOETHYL ALKENYLSUCCIAMIC ACID OF AN ALKENYL SUCCINIC ACID HAVING THE FORMULA: 